Figure 1-4. Precision vs. Accuracy

Archer A is neither accurate nor precise. Archer B is more accurate because her arrows are closer to the bull's-eye. Archer C is precise, since his arrows all hit the same spot, but is not accurate. Only archer D is both precise and accurate. (Unit 1, Section 2)

Figure 1-5. Iron Age Swords and Spearheads from Kirkburn, England

Shown here are a sword, scabbard (the sheath for holding the sword), and several spearheads, which date from around 300-200 BCE, during England's Iron Age. The sword and spearheads are made of iron and the scabbard has a decorated copper alloy front and an iron back. The detail on the sword indicates that it was made by a skilled metalworker. (Unit 1, Section 3)

Figure 1-8. Alembic from 13th-Century Tabriz

A 13th-century alembic made in Tabriz (now part of modern-day Iran), shown upside-down. An Arab chemist would distill a substance by heating it with the tube inverted over the liquid. Vapor would rise through the tube, cool under the large glass dome, and condense into the flask underneath it. (Unit 1, Section 4)

Figure 1-9. Philosopher's Stone

Sir Isaac Newton, one of the towering figures of modern science, also was fascinated by alchemy and the concept of a Philosopher's Stone. He may have believed that it would help him decipher scientific problems. (Unit 1, Section 5)

The roof of the Château Frontenac in Quebec City, Canada, shows the blue-green color associated with copper carbonate forming on the surface of copper roofing plates. This is a natural process whereby the elements of nature, including acid rain, heat, and sunlight, cause the copper roof to react. The reaction that took place on the copper roof is the reverse of the reaction that Proust had done when he was converting the copper carbonate back to copper metal. The second image shows a close-up of purified copper carbonate powder. (Unit 1, Section 7)

Figure 1-12. Owens Lake: A Mostly Dry Lake with Salt Deposits

Similar to the Natron lakes in Egypt, Owens Lake in California was a site for soda processing due to the salts that surrounded it as well. The reddish color around the lake now comes from bright pink halophilic (salt-loving) bacteria that grow on these deposits. (Unit 1, Section 7)

Figure 1-13. Elements and Their Combinations

A plate showing the elements from Dalton's New System of Chemical Philosophy. English chemist John Dalton proposed an early version of modern atomic theory that classified substances according to the mass of their particles. (Unit 1, Section 8)